Do not pass filename to UltiSnips#AddSnippet.

doc/UltiSnips.txt

@@ -387,11 +387,10 @@ UltiSnips provides some functions for extending core functionality.
  3.5.1 UltiSnips#AddSnippet                            *UltiSnips#AddSnippet*
 
 The first function is UltiSnips#AddSnippet(trigger, value, description,
-options, ...). It adds a new snippet with the provided trigger, value,
+options, filetyp="all"). It adds a new snippet with the provided trigger, value,
 description, and options to the current list of snippets. See
 |UltiSnips-syntax| for details on the meaning of the function arguments. All
-arguments are strings. An optional fifth argument can be used to specify the
-filetype for the new snippet.
+arguments are strings.
 
 
  3.5.2 UltiSnips#Anon                                        *UltiSnips#Anon*

pythonx/UltiSnips/providers/added_snippets_provider.py

@@ -1,14 +1,14 @@
 #!/usr/bin/env python
 # encoding: utf-8
 
-"""Handles manually added snippets (i.e. not in a file)."""
+"""Handles manually added snippets through UltiSnips#AddSnippet or
+UltiSnips_Manager.add_snippet()."""
 
 from UltiSnips.providers._base import SnippetProvider
 
 class AddedSnippetsProvider(SnippetProvider):
     """See module docstring."""
 
-    # TODO(sirver): filename makes no sense here. Is it even used?
-    def add_snippet(self, ft, snippet, filename):
+    def add_snippet(self, ft, snippet):
         """Adds the given 'snippet' for 'ft'."""
-        self._snippets[ft].add_snippet(snippet, filename)
+        self._snippets[ft].add_snippet(snippet, None)

pythonx/UltiSnips/snippet_manager.py

@@ -169,10 +169,10 @@ class SnippetManager(object):
 
     @err_to_scratch_buffer
     def add_snippet(self, trigger, value, description,
-                    options, ft="all", globals=None, fn=None):
+                    options, ft="all", globals=None):
         """Add a snippet to the list of known snippets of the given 'ft'."""
         self._added_snippets_provider.add_snippet(ft, SnippetDefinition(
-            trigger, value, description, options, globals or {}), fn
+            trigger, value, description, options, globals or {})
         )
 
     @err_to_scratch_buffer